straight talk refuses to unlock

I got it at walmart a few years ago and for a long time had no problems using it on my at&t service till recently when i inquired about that fact they stated that it must have been a "glitch" in there system that was caught and now they wont even let me try and activate it through their system because they stated it was showing as not being active and i would have to go back to the store and have it re-scanned which i cant do because i have the apple box but not anything with straight talk on it for them to be able to scan i have even emailed them pictures of the info on the phone showing what i have been telling them and what they asked for and that when they said that they would have to see the receipt after all this time and hung up rudely on me

And there my problem straight talk refuses to try and find a solution all the tech does is read from the same script and hangs up and refuses to even let me talk to someone higher up on the food chain with them swearing that it has never been active in there system is there anything one of these third party unlockers can do for me or would that even be a waste of time